Aerospace rotors, especially the new generation of rotors, can often have tolerances that translate to eccentricities measured in the millionths of inches.
Repeatability in the balancing world relates to how well the rotor’s intended spin axis and it’s principle axis of inertia are defined. Aligning two axis makes no sense if one or the other, or both, are moving around. Doing so is like trying to hit a moving target.
The tighter a rotor’s balancing tolerance, the more exact its intended spin axis must be defined. Since the tooling is responsible for holding the rotor, the responsibility for repeating the axis of rotation from one run to another, or after removing and replacing the rotor falls on the tooling. At a minimum, tooling must be able to define and repeat the axis of rotation to that eccentricity which corresponds with the rotor’s tolerance.
Meeting High Tolerance Requirements
Machining tolerances of thousandths, or tens of thousandths, may not always be easy to achieve but are certainly routine in the machining world. These capabilities have historically been acceptable because balancing tolerances were repeatable at these levels. Today, however, the game has changed. Engines are becoming lighter and faster. Many of these new generation engine components and modules require balancing tolerances unheard of just a few years ago. It is not uncommon for today’s tolerances to be discussed in terms of eccentricities that are measured in the millionths of inches. Industry must adapt to these new requirements by understanding and resolving the fact that repeatability in millionths of inches is impossible with tooling that repeats, at best, to tens of thousandths.
As a major manufacturer of aerospace grade balancing tooling VSN addresses repeatability challenges as a matter of course. Unfortunately, while our manufacturing capabilities push the limits of today’s technologies, using traditional methods does not allow for better tooling strides. Rather than following the usual paths, we have looked rather at how assembly methods can be used to resolve these issues. Kin-Dex™ has provided us that solution.
Expediting the Balancing Process
At the core of Vibration Solutions North’s approach to balancing is the Kin-Dex™* method of locating tooling for extreme repeatability and accuracy. The patent-pending Kin-Dex™ system uses kinematic mounting that indexes and locates parts on fixtures or tooling so that they can be demonstrated to extreme levels of accuracy and repeatability.
Kin-Dex™ helps remove the uncertainty from balancing operations and dramatically speeds up the process of mounting and dismounting tooling and components for balancing.
Kin-Dex™ tooling has been proven under very demanding conditions and is currently being used by Vibration Solutions North’s customers in the aerospace industry. It has been used by Moscow Mills extensively for fixturing and mounting components that must be machined to extreme tolerances.